Arowana are very calm and graceful swimmers, always at or near the top so you can see them, and are just plain good looking. I will Arowana bash a little with you though, although they are pretty nice I don't think it's worth it to have a 180 gallon or larger for a silver or black arowana, they're just not good enough to be worth it in my personal opinion, Asians and Australians are a different story, don't know if African aros are worth it, and Green Asians are just borderline worthwhile. And I'm not talking about prices, just what I like personally.